This invention relates generally to explosive welding techniques and specifically to a means of limiting the noise and products of the explosive process.
Explosive welding as presently practiced is an efficient method for bonding materials which are difficult to weld by more conventional means. It is particularly useful for thin materials which might suffer damage or change properties due to heat; for specific materials such as titanium or aluminum which have unique properties requiring a high degree of skill for conventional welds; and for large structures which require complex and expensive equipment to obtain uniform welds by conventional means.
Explosive welding is a comparatively simple procedure with which such materials may be bonded by relatively unskilled personnel. In such a technique the parts to be welded are spaced slightly apart by separators, jigs, or dimples and explosive is attached to one of the parts directly opposite the proposed bond area. The other part to be welded is rigidly supported on an anvil or table. Upon detonation of the explosive the parts to be welded are driven together with such force that they are metallurgically bonded. It is generally accepted that as the collision occurs remaining surface contaminants are stripped away, providing virgin metal for the metallurgical bond.
The tooling requirements for such an operation are very minimal. Satisfactory seam welds can be secured with only a cord-like preformed explosive, aluminum spacers, clamps, masking tape and a commercially available blasting cap detonator. The fabrication designer is able to specify all these items so that an unskilled person can perform the operation with reasonable certainty that a leak-proof bond will result. Because of the minimal tooling, low cost, and ability to weld aluminum and titanium, application of the explosive welding technique is anticipated in the aircraft industry and in extra-terrestrial applications. It is viewed as particularly applicable to the fabrication of space stations in orbit. Despite its advantages and the fact that the technique has been under development for almost twenty years, it has seen relatively little industrial use.
This may be because of the psychological effects of the noise and scattering of debris from the explosion. While such phenomena are relatively minor when a small amount of explosive is used, they do present some safety hazard and create a reluctance to the use of this otherwise valuable technique. This same explosive debris presents another problem in some applications. In high vacuum, space and other applications which require close control of potential contaminants, the explosive welding technique presents the problem of scattering debris into areas where it causes undesirable contamination. The present invention solves these problems without adding significantly to the complexity or cost of the basic technique.